Gas discharge lamp and method for making same

ABSTRACT

A gas discharge lamp has a glass tube which constitutes a first helix extending in the manner of a multi-turn screw thread from a first end portion, and a second helix encompassing the first helix. The second helix is interconnected with the first helix and extends in the manner of a multi-turn screw thread to a second end portion of the glass tube. Lamp electrodes are located in the mentioned first and second end portions. A gas filling is contained in the glass tube to provide the requisite gas discharge for emiting light from the lamp. The lamp may include a hollow-cylindrical echelon lens encompassing the first and second helices. This lens may have an annular oblate-spheroidal central portion encompassing the first and second helices.

United States Patent [191 Schmidt [451 on. 9, 1973 [54] GAS DISCHARGELAMP AND METHOD Primary Examiner-Roy Lake FOR MAKING SAME AssistantExaminer-Darwin R. l-Iostetter [76] Inventor: Alfred I. Schmidt, 6343Camellia Ave., North Hollywood, Calif. 91606 57 ABSTRACT 22 Filed: Apr.28, 1972 Appl. No.: 248,505

A gas discharge lamp has a glass tube which constitutes a first helixextending in the manner of a multiturn screw thread from a first endportion, and a second helix encompassing the first helix. The secondhelix is interconnected with the first helix and extends in the mannerof a multi-turn screw thread to a second end portion of the glass tube.Lamp electrodes are located in the mentioned first and second endportions. A gas filling is contained in the glass tube to provide therequisite gas discharge for emiting light from the lamp. The lamp mayinclude a hollow-cylindrical echelon lens encompassing the first andsecond helices. This lens may have an annular oblate-spheroidal centralportion encompassing the first and second helices.

10 Claims, 2 Drawing Figures GAS DISCHARGE LAMP AND METHOD FOR MAKINGSAME BACKGROUND OF THE INVENTION 1. Field of the Invention The subjectinvention relates to lighting and, more particularly, to gas dischargelamps and methods for making same.

2. Description of the Prior Art Gas discharge lamps typically have ahigher efficiency and a longer life than incandescent lamps. On theother hand, incandescent lamps typically are able to provide a moreconcentrated light source than gas discharge lamps.

This is a drawback in many applications. For instance, governmentrequirements,'such as Federal Aviation Administration regulations,provide for warning beacons and markers which have a high brilliancewithin a certain angular range relative to a horizontal plane, whilehaving a low brightness at angles beyond that range. So far, it has beenpossible to meet these re quirements with incandescent lamps providedwith echelon or Fresnel type lenses. However, efficient incandescentlamps have a rather limited life time. This has not only increased themaintenance cost of the particular lights, but has created dangeroussituations because of frequent inaction of warning or marker lights.

As may, for instance, be seen from US. Pat. No. 3,297,863, by F.Robbiano, issued Mar. 10, 1967, proposals have been made in the past toprovide a more concentrated gas discharge lamp by winding the glass tubeof the lamp in the form of spirals into adjacent flat planes. Thisproposal is, however, not suitable for solving the subject problem,since closely wound flat spiral glass tube structures are difficult tomanufacture and impart to the lamp excessive lateral dimensions,rendering it difficult for echelon type lenses to accommodate the lamp.Also, this type of spiral-wound lamp emits an excessive amount of lightin a vertical direction as seen from the above mentioned horizontalplane.

SUMMARY OF THE INVENTION It isan object of this invention to solve theabove mentioned problems.

It is a further object of this invention to provide a gas discharge lampwhich constitutes a more concentrated source of light.

It is a further object of the invention to provide a gas discharge lampwhich constitutes a more directional source of light.

It is a further object of this invention to provide warning lights,marker beacons and the like which employ gas discharge lamps and havecertain directional characteristics formerly attainable only withincandescent lamps.

Other objects will become apparent in the further course of thisdisclosure.

From one aspect thereof, the invention resides in a gas discharge lampcomprising, in combination, a glass tube having a first end portion anda second end portion, and constituting a first helix extending in themanner ofa multi-tum screw thread from the first end portion, and asecond helix encompassing the first helix, the second helix beinginterconnected with the first helix and extending in the manner of amulti-turn screw thread to the second end portion, first lamp electrodeand terminal means in and at the first end portion, second lampelectrode and terminal means in and at the second end portion, and a gasfilling in the glass tube.

The mathematical concept of a helix is well known. However, certainreference works loosely apply the expression helix to such things asflat spirals. Since this invention does not employ glass tubes which arewound in the form of flat spirals, the phrase helix extending in themanner of a multi-turn screw thread has been coined herein todistinguish the type of helices herein disclosed from flat spiralstructures.

In accordance with a preferred embodiment of this invention, the lampincludes a hollow lens structure encompassing the defined first andsecond helices. This lens may be a hollow-cylindrical echelon lens. Thelens may have an annular oblate-spherical central portion whichencompasses the two helices.

In the latter case, the first helix may extend essentially along a firstimaginary cylinder located inside of and being essentially concentricwith the hollowcylindrical lens, and the second helix may extendessentially along a second imaginary cylinder located inside of andbeing essentially concentric with the first imaginary cylinder.

Because of the geometrical configuration of the lamp according to thesubject invention, the lamp with the two helices has inherentdirectional characteristics which render staggered or Fresnel lensesunnecessary. Therefore, in accordance with a further preferred embodiment of the subject invention, the lamp includes a hollowcover'glass encompassing the first and second helices and having anessentially cylindrical outer surface and an essentially cylindricalinner surface.

Similarly, in accordance with a preferred embodiment of the subjectinvention, the lamp includes a hollow cover glass encompassing the firstand second helices and having a part laterally surrounding the first andsecond helices. At least the part laterally surrounding the first andsecond helices has an essentially uniform wall thickness.

In accordance with the presently most preferred embodiment of thesubject invention, one of the first and second helices extends in themanner of a righthand multi-turn screw thread, and the other of thefirst and second helices extends in the manner of a left-hand muIti-turnscrew thread. This embodiment is very advantageous since it provides forpart of a turn of each helix to appear in coincidence with gaps betweenthe turns of the other helix. In this manner, the continuity of thelateral light flux of the lamp is materially improved.

BRIEF DESCRIPTION OF THE DRAWINGS The invention and its objects willbecome more readily apparent from the following detailed description ofpreferred embodiments thereof, illustrated by way of example in theaccompanying drawings, in which:

FIG. 1 is an elevation, partially in section, of a lamp in accordancewith a first preferred embodiment of the subject invention; and

FIG. 2 is a side view, on a reduced scale, of a lamp in accordance witha second preferred embodiment of the subject invention.

DESCRIPTION OF PREFERRED EMBODIMENTS The gas discharge lamp 10 shown inFIG. 1 has a glass tube 12 having a first end portion 13 and a secondend portion 14. The glass tube 12 constitutes a first helix 16 extendingin the manner of a multi-turn screw thread from the first end portion13. The glass tube 12 further constitutes a second helix 17 whichencompasses the first helix 16 and which is interconnected with thefirst helix at 18. The second helix 17 extends in the manner of amulti-turn screw thread to the second end portion 14. 3

In the illustrated preferred embodiment, the first helix 16 extends inthe manner of a right-hand multiturn screw thread, and the second helix17 extends in the manner of a left-hand multi-turn screw thread. Thishas the substantial advantage of providing behind each gap betweenadjacent turns of the helix 17 a part of a turn of the helix 16, and ofcovering up substantially each gap between adjacent turns of the helix16 with part of a turn of the helix 17. As a result, the continuity ofthe lateral light flux from the lamp is substantially improved overversions in which both helices are wound in the same sense. The sameadvantage may be realized by winding the helix 16 in the manner of amult-turn left-hand screw thread and the helix 17 in the manner of amulti-turn right-hand screw thread.

The lamp further has a lamp electrode 20 with terminal means 21 in andat the first end portion 13, and a lamp electrode 23 and terminal means22 in and at the second end portion 14. These lamp electrode andterminal means may be provided in a conventional manner.

The lamp 10 also includes a gas filling in the glass tube 12. This gasfilling may be provided in a conventional manner, such as by evacuatingthe glass tube and then inserting a gas charge into the evacuated glasstube. A point 23 shown in FIG. 1 constitutes the melted-down version ofan evacuation and gas filling tube (not shown) for the glass tube 12.

By way of example and in accordance with conventional practice, neon canbe provided in the glass tube 12 for a red light output, and helium canbe employed for a cream color light output. The term gas filling is notused herein in a restrictive sense and is intended to be broad enough tocover argon and mercury fillings, which provide a blue light output, aswell as other compound or gas fillings for desired light effects. It isalso to be understood that fluorescent powders may be used in the lamp10 to provide or enhance a desired color effect of the generated light.

In the illustrated preferred embodiment of FIG. 1, the lower parts ofthe end portions 13 and 14 are cemented in a socket 25. The socket 25has an outer ring 26 which may be of metal or of an electricallyinsulating material and a cement filling 26 which is of an electricallyinsulating cement or synthetic resin.

The terminal means 21 and 22 extend through the socket 25 into highvoltage equipment 28. The high voltage equipment 28 may, for instance,include a high voltage transformer which transforms line voltagereceived from leads 29 into the requisite high voltage needed for theoperation of the lamp 10. High voltage equipment of this type isconventional and is, therefore, not described or illustrated in detailherein. The showing of the high voltage equipment 28 is, accordingly,highly schematic and it should be understood that the high voltagetransformer may be located outside of the lamp structure shown in FIG.1.

or Fresnel-type lens 36 which encompasses the first and second helicesl6 and 17.

A gasket 38 is located between the top of the lamp base 33 and ashoulder 39 of the lens 36 to prevent the intrusion of water into thelamp structure.

The echelon lens 36 has an annular oblate-spheroidal central portion 42encompassing the first and second helices. The lens also includes aplurality of saw-tooth shaped annular ribs 43 and 44 for enhancing thedirectional effect of the lens on the light generated by the lamp.

The lens 36 may be made of glass or of a transparent organic substitutetherefor.

Reverting to the helices l6 and 17, it may be seen that the first helix16 may be considered as extending essentially along a first imaginarycylinder located inside of and substantially concentric with the lens36. Similarly, the second helix 17 may be considered as extendingessentially along a second imaginary cylinder located inside of andbeing essentially concentric with the first imaginary cylinder. Thisdistinguishes the lamp according to the subject invention from suchstructures as the lamp structure shown in the above mentioned Robbianopatent in which the lamp is composed of two flat spirals which extendalong parallel imaginary flat planes.

In contrast to the lamp of FIG. 1, the lamp 51 according to thepreferred embodiment of FIG. 2 does not have a hollow lens structure.Rather, it has a hollow cover glass 52 which encompasses first andsecond helices 16 and 17 and which has an essentially cylindrical outersurface 53 and an essentially cylindrical inner surface 54. The coverglass need not necessarily be cylindrical, as long as at least the part56 of the cover glass which laterally surrounds the first and secondhelices 15 and 16 has an essentially uniform wall thickness, as shown inFIG. 2.

The possibility of using a simple type of glass cover instead of anexpensive echelon or Fresnel type lens structure is rendered possible bythe directional characteristics of the dual helix lamp configurations ofthe subject invention.

It should also be noted at this juncture that a special coloration ofthe lens structure 36 or of the cover glass 51 is rendered unnecessaryby the fact that a desired coloration of the generated light may beprovided by an appropriate gas filling of the helices 16 and 17 with orwithout the use of metallic or other additions of fluorescent powders.

The expression cover glass is herein employed in a broad sense since itis intended to cover not only glass but also organic substitutesthereof. The lamp of the subject invention may be manufactured byconventional techniques. For instance, a cylindrical or threaded mandrelmay be employed for winding the inner helix 16 and a hollow-cylindricalmandrel of a similar type may then be employed for winding the outerhelix 17 from a heated glass tube.

It will now be recognized that the subject invention providessubstantial technological advances in the gas discharge lamp field.Variations and modifications within the spirit and scope of the subjectinvention will suggest themselves or become apparent from the subjectdisclosure to those skilled in the art.

I claim: 1. A gas discharge lamp comprising in combination: a glass tubehaving a first end portion and a second end portion, and constituting afirst helix extending in the manner of a multi-turn screw thread fromsaid first end portion, and a second helix encompassing said firsthelix, said second helix being interconnected with said first helix andextending in the manner of a multi-turn screw thread to said second endportion; first lamp electrode and terminal means in and at said firstend portion; second lamp electrode and tenninal means in and at saidsecond end portion; and a gas filling in said glass tube. 2. A lamp asclaimed in claim 1, including in said combination:

a hollow lens structure encompassing said first and second helices. 3. Alamp as claimed in claim 1, including in said combination:

a hollow echelon lens encompassing said first and second helices. 4. Alamp as claimed in claim 3, wherein: said lens has an annularoblate-spheroidal central portion encompassing said first and secondhelices. 5. A lamp as claimed in claim 4, wherein: said first helixextends essentially along a first imaginary cylinder located inside ofand being essentially concentric with said lens; and said second helixextends essentially along a second imaginary cylinder located inside ofand being essentially concentric with said first imaginary cylinder.

6. A lamp as claimed in claim 1, including in said combination:

a hollow cover glass encompassing said first and second helices andhaving an essentially cylindrical outer surface and an essentiallycylindrical inner surface.

7. A lamp as claimed in claim 1, including in said combination:

a hollow cover glass encompassing said first and second helices andhaving a part laterally surrounding said first and second helices, atleast said part laterally surrounding said first and second heliceshaving an essentially uniform wall thickness.

8. A gas discharge lamp comprising in combination:

a glass tube having a first end portion and a second end portion, andconstituting a first helix extending in the manner of a multi-turn screwthread from said first end portion, and a second helix encompassing saidfirst helix, said second helix being interconnected with said firsthelix and extending in the manner of a multi-turn screw thread to saidsecond end portion, one of said first and second helices extending inthe manner of a right-hand multiturn screw thread, and the other of saidfirst and second helices extending in the manner of a lefthandmulti-turn screw thread;

first lamp electrode and terminal means in and at said firs end portion;

second lamp electrode and terminal means in and at said second endportion; and

a gas filling in said glass tube.

9. A gas discharge lamp as claimed in claim 8, including in saidcombination:

a hollow cover glass encompassing said first and second helices andhaving an essentially cylindrical outer surface and an essentiallycylindrical inner surface.

10. A gas discharge lamp as claimed in claim 8, in-

cluding in said combination:

a hollow cover glass encompassing said first and second helices andhaving a part laterally surrounding said first and second helices, atleast said part laterally surrounding said first and second heliceshaving an essentially uniform wall thickness.

1. A gas discharge lamp comprising in combination: a glass tube having afirst end portion and a second end portion, and constituting a firsthelix extending in the manner of a multi-turn screw thread from saidfirst end portion, and a second helix encompassing said first helix,said second helix being interconnected with said first helix andextending in the manner of a multi-turn screw thread to said second endportion; first lamp electrode and terminal means in and at said firstend portion; second lamp electrode and terminal means in and at saidsecond end portion; and a gas filling in said glass tube.
 2. A lamp asclaimed in claim 1, including in said combination: a hollow lensstructure encompassing said first and second helices.
 3. A lamp asclaimed in claim 1, including in said combination: a hollow echelon lensencompassing said first and second helices.
 4. A lamp as claimed inclaim 3, wherein: said lens has an annular oblate-spheroidal centralportion encompassing said first and second helices.
 5. A lamp as claimedin claim 4, wherein: said first helix extends essentially along a firstimaginary cylinder located inside of and being essentially concentricwith said lens; and said second helix extends essentially along a secondimaginary cylinder located inside of and being essentially concentricwith said first imaginary cylinder.
 6. A lamp as claimed In claim 1,including in said combination: a hollow cover glass encompassing saidfirst and second helices and having an essentially cylindrical outersurface and an essentially cylindrical inner surface.
 7. A lamp asclaimed in claim 1, including in said combination: a hollow cover glassencompassing said first and second helices and having a part laterallysurrounding said first and second helices, at least said part laterallysurrounding said first and second helices having an essentially uniformwall thickness.
 8. A gas discharge lamp comprising in combination: aglass tube having a first end portion and a second end portion, andconstituting a first helix extending in the manner of a multi-turn screwthread from said first end portion, and a second helix encompassing saidfirst helix, said second helix being interconnected with said firsthelix and extending in the manner of a multi-turn screw thread to saidsecond end portion, one of said first and second helices extending inthe manner of a right-hand multi-turn screw thread, and the other ofsaid first and second helices extending in the manner of a left-handmulti-turn screw thread; first lamp electrode and terminal means in andat said first end portion; second lamp electrode and terminal means inand at said second end portion; and a gas filling in said glass tube. 9.A gas discharge lamp as claimed in claim 8, including in saidcombination: a hollow cover glass encompassing said first and secondhelices and having an essentially cylindrical outer surface and anessentially cylindrical inner surface.
 10. A gas discharge lamp asclaimed in claim 8, including in said combination: a hollow cover glassencompassing said first and second helices and having a part laterallysurrounding said first and second helices, at least said part laterallysurrounding said first and second helices having an essentially uniformwall thickness.